crash after setting root background to None, then setting color - patch for review

[Marko Macek]

Hello!

Please review/apply this patch:

diff -ru xorg-server-1.10.1/dix/window.c xorg-server-1.10.1-new/dix/window.c
--- xorg-server-1.10.1/dix/window.c    2011-02-25 04:27:25.000000000 +0100
+++ xorg-server-1.10.1-new/dix/window.c    2011-05-15 15:15:03.912919996 +0200
@@ -474,6 +474,7 @@
          pWin->background.pixel = pScreen->whitePixel;
          backFlag |= CWBackPixmap;
      } else {
+    pWin->backgroundState = BackgroundPixel;
      if (whiteRoot)
              pWin->background.pixel = pScreen->whitePixel;
          else
@@ -972,6 +973,7 @@
      else if (party_like_its_1989)
      MakeRootTile(pWin);
      else {
+    pWin->backgroundState = BackgroundPixel;
      if (whiteRoot)
          pWin->background.pixel = pScreen->whitePixel;
      else


This is valgrind output:

==2514== Process terminating with default action of signal 11 (SIGSEGV)
==2514==  General Protection Fault
==2514==    at 0x37A60F5185: __sprintf_chk (sprintf_chk.c:28)
==2514==    by 0x4616B4: LogVWrite (stdio2.h:34)
==2514==    by 0x4613EA: ErrorF (log.c:561)
==2514==    by 0x4A13CD: xorg_backtrace (backtrace.c:44)
==2514==    by 0x4622C5: OsSigHandler (osinit.c:136)
==2514==    by 0x37A640F3BF: ??? (in /lib64/libpthread-2.13.90.so)
==2514==    by 0x4B88BC: ShmDestroyPixmap (privates.h:158)
==2514==    by 0x4573E2: ChangeWindowAttributes (window.c:1086)
==2514==    by 0x42923F: ProcChangeWindowAttributes (dispatch.c:692)
==2514==    by 0x42EC10: Dispatch (dispatch.c:431)
==2514==    by 0x422E19: main (main.c:287)
==2514==

The situation that causes an xserver crash is this:

1. XSetWindowBackground(..., root, None)
2. followed by XSetWindowBackground(...)


The code could also be made more robust (check for pixmap != None, set it to None after Destroy). Should I do it?

     Mark